1. Field of the Invention
The present invention relates to a conduit end fitting for a motion transmitting remote control cable assembly of the type used in transmission shift cables, park brake cables and light duty control cables and a method for making such a fitting.
2. Background Art
Motion transmitting remote control cable assemblies are used for transmitting both force and travel along a curved path in aircraft, automotive, and marine environments. Known cable assemblies can be used for transmitting load and motion in both push and pull type applications. In the automotive environment, typical applications include but are not limited to parking brake, accelerator, hood release, brake release, trunk release, park lock, tilt wheel control, fuel filler door, transmission shifter cables and hydraulic control cables. One specific use of such remote control assemblies is the positioning of throttle and transmission shift members in automobiles.
Motion transmitting remote control assemblies for transmitting motion in a curved path typically include flexible core element (strand) slidably enclosed within a flexible outer sheath (conduit) with end fittings attached to both ends of each respective member. These fittings attach to and react load from the conduit to its mounting points and from the strand to its mounting points respectively. The core element is adapted at one end to be attached to a member to be controlled whereas the other end is attached to a manual actuator for longitudinally moving the core element. Thus, in the automotive environment, for example, assemblies normally include one or more fittings secured to the conduit for attaching the conduit to a support structure of the automobile.
The conduit end fittings must remain attached to the conduit while resisting relative axial movement (lash) between the conduit and the conduit end fittings. These conduit end fittings may be attached to the conduit in many ways, which can include: over molding, gluing, press fitting, screw on, spin welding, staking as well as many other methods. Although all these methods provide for a strong joint that resists axial movement, unfortunately, they all eliminate relative rotational movement between the conduit and the conduit end fittings.
Having the conduit end fittings fixed against rotation relative to the conduit creates a problem in that, during the assembly operation, the operator frequently has to twist the conduit end fitting along the axis of the conduit in order to line it up and install it in the mounting point. When the conduit end fitting is fixed against rotation relative to the conduit, this twisting operation has the detrimental effect of, among other things, slowing down the assembly process and twisting and binding the conduit. To eliminate the assembly problems, it is desirable to have conduit end fittings on the conduit that provide for easy rotation about the axis of the conduit, and thus speed up the assembly time and reduce binding and twisting of the conduit.
One example of a known conduit end fitting product is shown in FIG. 1. As shown, the control cable 10 includes a conduit 12 and a wire-like strand or core element 14. The end of the strand 14 is attached to a slider rod 16 that extends within a swivel tube 18. The swivel tube 18 is supported within a swivel socket provided an the conduit end fitting. The conduit end fitting of this prior art design includes a hard plastic sleeve 8 molded onto an end of the conduit. A compressible isolator 9 is molded or pressed over the molded sleeve. The sleeve and isolator are tapered toward the end of the conduit and contained within molded outer fitting 2. A spherical cavity or socket 2s for receiving the swivel tube is formed entirely within the outer fitting 2 at the one of the conduit end fitting. The opposite end of the conduit end fitting, i.e., the end that receives the conduit, is capped with a cap, which is typically formed of metal. This design does not, however, include any means to facilitate rotation of the end fitting relative to the conduit.
In addition, because the spherical socket or cavity for receiving the swivel tube 18 is formed entirely within the outer fitting 2, the swivel tube must be snapped into the socket during assembly. As a consequence, the spherical extent of the socket is limited and the degree to which the swivel tube is securely retained within the socket is also limited.
It is known to make conduit end fittings that rotate about the axis of the conduit. Conduit end fittings that rotate about the axis of the conduit are shown, for example, in U.S. Pat. Nos. : 4,860,609; 4,951,524; 5,161,428 and 5,383,377.
U.S. Pat. No. 4,860,609 discloses a flexible motion transmitting core element that includes a conduit (12), a flexible motion transmitting core element (14) that is slidably supported by the conduit and a connector member (16) that includes an annular radially extending flange (18). The assembly (10) further includes an end fitting (30) having a cylindrical portion (32). The cylindrical portion (32) is positioned over the outer surface of the connector member (16) such that the cylindrical portion (32) abuts the flange (18). A retainer (38) simultaneously engages the end fitting (30) and the flange (18) for preventing relative axial movement between the conduit (12) and the end fitting (30) while permitting relative rotational movement therebetween.
U.S. Pat. No. 4,951,524 discloses a flexible motion transmitting core element (28) that includes a supporting fitting (14) having first and second ends defining a first axis for extending through a substantially U-shaped seat (18) in a support structure (20). A core element (28) is movably supported by the support fitting (14) for transmitting motion between the ends thereof. The assembly (10) includes a pair of spaced flanges (52, 52', 54, 54o) supported about the support fitting (14) for allowing relative rotation therebetween and positioning the support fitting (14) in the substantially U-shaped seat (18) on the support structure (20).
U.S. Pat. No. 5,161,428 discloses a motion transmitting remote control assembly (10) for transmitting forces along a curved path by a flexible core element (26) slidably disposed within a flexible conduit (12). The assembly (10) includes an elongated member (62) for adjusting the longitudinal position of the conduit (12) by being slidably disposed within a passageway (68) of a support member (32). A locking clip (86) is movable between a disengaged position for permitting relative longitudinal movement between the elongated member (62) and the base (32) and an engaged position for preventing longitudinal movement therebetween. The elongated member (62) is rotatably supported on the conduit (12) to allow rotation of the conduit (12) relative to the support member (32) while in an engaged position.
U.S. Pat. No. 5,383,377 discloses a flexible motion transmitting core element (54) that includes a conduit (12) and a cable (54) that is movably supported along its length within the conduit (12). A support member (48) attaches one end (14) of the conduit (12) to a support structure (46). An isolator (96) is disposed between the support member (48) and the conduit end (14). The conduit end (14) has an integral conduit end fitting (18). The isolator (96) dampens vibrations and shocks transmitted between the support member (48) and the conduit end (14). The isolator (96) is fixed against translational movement relative to the conduit end (14). An anti-stick coating (106) disposed on the outer surface (100) of the conduit end fitting (18) allows the conduit end (14) and conduit end fitting (18) to rotate relative to the support member (48).
The assemblies described in these patents each have some disadvantage, however. For example, the fittings may introduce extra lash into the cable assembly, which in turn reduces the travel efficiency of the push pull cable system. The fittings may also complicate assembly and increase capital and labor expense.
Another known assembly is described in U.S. Pat. No. 4,726,251, which discloses a flexible core element (12) in a conduit (18) and a method of making same. An end fitting (20) is disposed about the conduit (18) by a cylindrical section which includes abutments (24). A vibration dampener (16) includes a cylindrical tube disposed about the end fitting (20) with grooves (28) aligned with the abutments (24) and tabs (30) extending radially outward from the vibration dampener (16). A support (14) includes a cylindrical wall (32) disposed about and coextensive with the vibration dampener (16) with openings (34) aligned with the tabs (30) of the vibration dampener (16). The vibration dampening means (16) is in axial mechanical interlocking engagement with the end fitting (20) and support (14) for maintaining the vibration dampener (16) free of radial compressive forces.
Likewise, U.S. Pat. No. 4,793,050 discloses a flexible core element (12) in a conduit (18) and a method of making same. An end fitting (20) is disposed about the conduit (18) by a cylindrical section which includes abutments (24). A vibration dampener (16) includes a cylindrical tube disposed about the end fitting (20) with grooves (28) aligned with the abutments (24) and tabs (30) extending radially outward from the vibration dampener (16). A support (14) includes a cylindrical wall (32) disposed about and coextensive with the vibration dampener (16) with openings (34) aligned with the tabs (30) of the vibration dampener (16). The vibration dampener (16) is in axial mechanical interlocking engagement with the end fitting (20) and support (14) for maintaining the vibration dampener (16) free of radial compressive forces.
U.S. Pat. No. 5,003,838 discloses a flexible motion transmitting core element assembly (10) that includes a conduit (16) with a male end fitting (20) molded at one end, which engages with a female end fitting (30). The female end fitting (30) includes a conduit (38) and attaches to a support structure (90). Splining (24, 32) is provided on the engaging portions of the male end fitting (20) and the female end fitting (30) to allow for precise rotational adjustment and locking between the male end fitting (20) and the female end fitting (30).
U.S. Pat. No. 4,406,177 and U.S. Pat. No. 4,348,348 disclose a flexible motion transmitting core element that includes a flexible motion transmitting core element and a flexible conduit. An end fitting is disposed about the end portion of the conduit for supporting the conduit and core element with the core element extending from the end fitting. The assembly also includes a support housing for supporting the end fitting and the conduit on a support structure. A resilient vibration dampener is disposed between the support housing and the end fitting for providing noise and vibration isolation therebetween. A mold assembly and a method are also disclosed for making the motion transmitting remote control assembly including the steps of; inserting the end portion of the conduit into a cavity of a first mold and injecting organic polymeric material into the cavity for molding the end fitting about the conduit, inserting the end fitting into a cavity of a second mold and injecting a vibration dampening material into the mold for molding a vibration dampener about the end fitting, and placing the vibration dampener into a cavity of a third mold and injecting an organic polymeric material for molding a support housing about the vibration dampener.
Similarly, U.S. Pat. No. 4,386,755 discloses a mold assembly and a method for making a motion transmitting remote control assembly including the steps of; inserting the end portion of the conduit into a cavity of a first mold and injecting organic polymeric material into the cavity for molding the end fitting about the conduit, inserting the end fitting into a cavity of a second mold and injecting a vibration dampening material into the mold for molding a vibration dampener about the end fitting, and placing the vibration dampener into a cavity of a third mold and injecting an organic polymeric material for molding a support housing about the vibration dampener.
Notwithstanding these prior art disclosures, there remains a need for an end fitting for a remote control cable assembly that is easy to assemble and allows for easy rotation of the end fittings relative to the axis of the conduit and does not add additional lash into the cable system from the rotating end fitting joint.